Synthetic attachment medium for cell culture

ABSTRACT

An aqueous cell culture medium composition includes an aqueous cell culture solution configured to support the culture of mammalian cells. The composition further includes a synthetic polymer conjugated to a polypeptide dissolved in the aqueous cell culture solution. The synthetic polymer conjugated to a polypeptide is configured to attach to the surface of a cell culture article under cell culture conditions. Incubation of the aqueous cell culture medium composition on a cell culture surface under cell culture conditions results is attachment to the surface of the synthetic polymer conjugated to the polypeptide.

This application claims the benefit of priority under 35 U.S.C. § 119 ofU.S. Provisional Application Ser. No. 61/594,016 filed on Feb. 2, 2012the content of which is relied upon and incorporated herein by referencein its entirety.

FIELD

The present disclosure relates to cell culture, and more particularly tomedia for cell culture containing synthetic, chemically-defined polymersand methods for cell culture and for coating substrates using suchmedia.

BACKGROUND

Therapeutic cells, cells which may be introduced into a human for thetreatment of disease, are being developed. Examples of therapeutic cellsinclude stem cells such as human embryonic stem cells (hESCs) and humanmesenchymal stem cells (hMSCs). which have the ability to differentiateto various cell types in the human body. This property of stem cellsprovides a potential for developing new treatments for a number ofserious cell degenerative diseases, such as diabetes, spinal cordinjury, heart diseases and the like. However, there remain obstacles inthe development of such cell-based treatments.

Obtaining and maintaining adequate numbers of therapeutic cells in celland tissue culture and ensuring that these cells do not change inunwanted ways during cell culture are important in developing andcontrolling therapeutic cell cultures. For example, stem cell culturesare typically seeded with a small number of cells from a cell bank orstock and then amplified in the undifferentiated or partiallydifferentiated state until differentiation is desired for a giventherapeutic application. To accomplish this, the stem cell or theirdifferentiated cells are typically cultured in the presence of surfacesor media containing animal-derived components, such as feeder layers,serum, or Matrigel™ available from BD Biosciences, Franklin Lakes N.J.These animal-derived additions to the culture environment may expose thecells to potentially harmful viruses or other infectious agents whichcould be transferred to patients or which could compromise generalculture and maintenance of the hESCs. In addition, such biologicalproducts are vulnerable to batch variation, immune response and limitedshelf-life.

Recently, synthetic surfaces that are free of animal-derived componentshave been shown to be successful in the culture of stem cells inchemically defined medium, addressing many of the issues that resultfrom culturing cells in the presence of animal-derived components.However, such synthetic surfaces have been made with high concentrationsof recombinant polypeptides, which can be expensive to manufacture. Insome cases, synthetic surfaces require the use organic solvents forpurposes of coating, as water soluble coating materials often cannotadequately remain bound to a surface under cell culture conditions.

BRIEF SUMMARY

Among other things, the present disclosure describes peptide-polymerscapable of supporting growth and attachment of stem cells in chemicallydefined medium, where the peptide-polymers may be added to cell culturemedium as a supplement to enhance cell attachment to uncoated surfaces.The peptide polymers have been found to form stable coatings on cellculture substrate surfaces when introduced as a supplement to cellculture media.

In various embodiments described herein, an aqueous cell culture mediumcomposition comprises (i) an aqueous cell culture solution configured tosupport the culture of mammalian cells; and (ii) a synthetic polymerconjugated to a polypeptide dissolved in the aqueous cell culturesolution, wherein the synthetic polymer conjugated to a polypeptide isconfigured to attach to the surface of a cell culture article under cellculture conditions, and wherein incubation of the aqueous cell culturemedium composition on a cell culture surface under cell cultureconditions results in attachment to the surface of the synthetic polymerconjugated to the polypeptide. The cell culture medium may be achemically defined composition or may be substantially free of organicsolvents. In embodiments, the polymer has a linear backbone and iscrosslink free, wherein the synthetic polymer conjugated to thepolypeptide is soluble in water at 20° C. or less. In embodiments, thecell culture medium comprises glucose and one or more amino acids.

In embodiments, a method described herein comprises (i) introducing asynthetic polymer having a covalently attached polypeptide to an aqueouscell culture medium to produce a polymer containing cell culture medium,wherein the synthetic polymer conjugated to a polypeptide is configuredto attach to the surface of a cell culture article under cell cultureconditions; (ii) disposing the polymer containing cell culture medium onthe surface of the cell culture article to produce a coated article; and(iii) incubating the coated article in the medium under cell cultureconditions (e.g., at 37° C.) to attach the synthetic polymer conjugatedto the polypeptide to the surface of the cell culture article. Thesurface of the substrate may have a water contact angle between 0° and50°. In embodiments, the surface of the substrate is a plasma treatedpolystyrene surface. The method may further include incubating cells(such as stem cells; e.g., human mesenchymal stem cells or humanembryonic stem cells) on the coated article in the medium under cellculture conditions. The method may further comprise introducing cellsinto the polymer containing cell culture medium prior to contacting thepolymer containing cell culture medium to the surface of the cellculture article.

One or more embodiments of the cell culture articles, compositions, ormethods described herein provide one or more advantages over prior cellculture articles, compositions, or methods for producing coated cellculture articles. For example, because the coating is fully synthetic,it does not suffer from batch variation, immune response, limitedshelf-life and risk of exposure of the cells to potentially harmfulviruses or other infectious agents which could be transferred topatients. In various embodiments, the coating is formed in situ from apeptide polymer present in a cell culture medium under typical cellculture conditions. These and other advantages will be readilyunderstood from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a reaction scheme for making a poly(MAA-PEG4-VN) homopolymerhaving a conjugated cell adhesive polypeptide.

FIG. 2 is a reaction scheme for making a poly(HEMA-co-MAA-PEG4-VN)copolymer having a conjugated cell adhesive polypeptide.

FIGS. 3A-B are schematic diagrams of side views of coated articles.

FIGS. 4A-C are schematic diagrams of cross sections of cell culturearticles having a well. Uncoated (4A); coated surface (4B); and coatedsurface and side walls (4C).

FIGS. 5a-c are images of human mesenechymal stem cells (hMSCs) culturedon different surfaces in chemically defined medium with our withoutattachment supplement: (a) on TCT surface precoated with MesenCult-XFAttachment Substrate (MC-ASB); (b) on TCT surface in medium supplementedwith 0.037 mg/ml MC-ASB; on TCT surface in medium supplemented with0.0074 mg/ml MC-ASB.

FIGS. 6a-f are images of hMSCs cultured on different surfaces inchemically defined medium with or without attachment supplement: (a) onpolyHEMA-co-VN precoated CellBind® surface; (b) on CellBind® surfacewithout attachment supplement; (c) on CellBind® surface in mediasupplemented with 0.006 mg/ml polyHEMA-co-VN; (d) on CellBind® surfacein media supplemented with 0.012 mg/ml polyHEMA-co-VN; (e) on CellBind®surface in media supplemented with 0.025 mg/ml polyHEMA-co-VN; (f) onCellBind® surface in media supplemented with 0.050 mg/ml polyHEMA-co-VN.

FIGS. 7a-i are images of crystal violet stained hMSCs cultured ondifferent surfaces in chemically defined medium with or withoutattachment supplement: (a) on TCT surface precoated with MC-ASB; (b) onTCT surface in medium supplemented with 0.037 mg/ml MC-ASB; (c) on TCTsurface in medium supplemented with 0.0074 mg/ml MC-ASB; (d) onpolyHEMA-co-VN pre-coated CellBind® surface; (e) on CellBind® surfacewithout supplement; (f) on CellBind® surface in media supplemented with0.006 mg/ml polyHEMA-co-VN; (g) on CellBind® surface in mediasupplemented with 0.012 mg/ml polyHEMA-co-VN; (h) on CellBind® surfacein media supplemented with 0.025 mg/ml polyHEMA-co-VN; (i) (c) onCellBind® surface in media supplemented with 0.050 mg/ml polyHEMA-co-VN.

FIG. 8 is a bar graph showing the percentage of viable hMSCs cultured onvarious surfaces in chemically defined medium.

FIG. 9 is a bar graph showing the cell density (cells/cm²) of hMSCscultured on various substrates in chemically defined medium.

FIGS. 10a-c are images of human embryonic stem cells (hESCs) cultured onvarious surfaces for two days in chemically defined medium with orwithout attachment supplement: (a) on CellBind® surface in mediasupplemented with 0.025 mg/ml polyHEMA-co-VN; (b) on CellBind® surfacein media supplemented with 0.006 mg/ml polyHEMA-co-VN; on Matrigel®coated control surface.

FIGS. 11a-c are images of hESCs cultured on various surfaces for fourdays in chemically defined medium with or without attachment supplement:(a) on CellBind® surface in media supplemented with 0.025 mg/mlpolyHEMA-co-VN; (b) on CellBind® surface in media supplemented with0.006 mg/ml polyHEMA-co-VN; on Matrigel® coated control surface.

FIG. 12 is a bar graph showing average cell number of hESCs cultured onvarious surfaces.

The schematic drawings are not necessarily to scale. Like numbers usedin the figures refer to like components, steps and the like. However, itwill be understood that the use of a number to refer to a component in agiven figure is not intended to limit the component in another figurelabeled with the same number. In addition, the use of different numbersto refer to components is not intended to indicate that the differentnumbered components cannot be the same or similar.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which are shown byway of illustration several specific embodiments of devices, systems andmethods. It is to be understood that other embodiments are contemplatedand may be made without departing from the scope or spirit of thepresent disclosure. The following detailed description, therefore, isnot to be taken in a limiting sense.

All scientific and technical terms used herein have meanings commonlyused in the art unless otherwise specified. The definitions providedherein are to facilitate understanding of certain terms used frequentlyherein and are not meant to limit the scope of the present disclosure.

As used in this specification and the appended claims, the singularforms “a”, “an”, and “the” encompass embodiments having pluralreferents, unless the content clearly dictates otherwise. As used inthis specification and the appended claims, the term “or” is generallyemployed in its sense including “and/or” unless the content clearlydictates otherwise.

As used herein, “have”, “having”, “include”, “including”, “comprise”,“comprising” or the like are used in their open ended sense, andgenerally mean “including, but not limited to”. It will be understoodthat “consisting essentially of”, “consisting of”, and the like aresubsumed in “comprising” and the like.

As used herein, “conjugated,” as it relates to a monomer or polymer anda polypeptide, means that the polypeptide is covalently bound, eitherdirectly or indirectly (e.g., via a spacer) to the polymer or monomer.

As used herein, “monomer” means a compound capable of polymerizing withanother monomer, (regardless of whether the “monomer” is of the same ordifferent compound than the other monomer).

As used herein, a “(meth)acrylate monomer” means a methacrylate monomeror an acrylate monomer. As used herein “(meth)acrylamide monomer” meansa methacrylamide or an acrylamide monomer. (Meth)acrylate and(meth)acrylamide monomers have at least one ethylenically unsaturatedmoiety. “Poly(meth)acrylate”, as used herein, means a polymer formedfrom one or more monomers including at least one (meth)acrylate monomer.“Poly(meth)acrylamide”, as used herein, means a polymer formed from oneor more monomers including at least one (meth)acrylamide monomer.

As used herein, a polymer without conjugated polypeptide that is“substantially similar” to a polymer conjugated to the polypeptide is apolymer that formed in the same manner as the polymer conjugated to thepolymer conjugated to the polypeptide except that the polypeptide is notincluded. For example, a polypeptide may be conjugated to a polymer viagrafting after the polymer is formed. In such cases, the substantiallysimilar polymer that is not conjugated to the polypeptide is the polymerthat has not been grafted. By way of further example, a monomer may bederivatized with a polypeptide and the polypeptide may be incorporatedinto the polymer as the monomer is polymerized or copolymerized. In suchcases, the substantially similar polymer that is not conjugated to thepolypeptide is a polymer formed under the same reaction conditions asthe polymer conjugated to the polypeptide except that the monomer is notderivatized with the polypeptide.

Polypeptide sequences are referred to herein by their one letter aminoacid codes or by their three letter amino acid codes. These codes may beused interchangeably.

As used herein, “peptide” and “polypeptide” mean a sequence of aminoacids that may be chemically synthesized or may be recombinantlyderived, but that are not isolated as entire proteins from animalsources. For the purposes of this disclosure, peptides and polypeptidesare not whole proteins. Peptides and polypeptides may include amino acidsequences that are fragments of proteins. For example peptides andpolypeptides may include sequences known as cell adhesion sequences suchas RGD. Polypeptides may be of any suitable length, such as betweenthree and 30 amino acids in length. Polypeptides may be acetylated (e.g.Ac-LysGlyGly) or amidated (e.g. SerLysSer-NH₂) to protect them frombeing broken down by, for example, exopeptidases. It will be understoodthat these modifications are contemplated when a sequence is disclosed.

As used herein, “chemically-defined medium” means cell culture mediathat contains no components of unknown composition. Chemically definedmedia may, in various embodiments, contain no proteins or hydrosylates.

In embodiments, the polymers and polypeptides described herein are“synthetic.” That is, they do not contain ingredients that are derivedfrom animals or animal extracts. Polymers or monomers may be conjugatedto polypeptides (“polymer—polypeptide” or “monomer—polypeptide”).Polypeptides may be synthesized or obtained through recombinanttechniques, making them synthetic, non-animal-derived materials.

The present disclosure describes, among other things, compositions andmethods for culturing cells or for coating cell culture articles. Thecompositions and methods include a synthetic polymer having a conjugatedpolypeptide. The synthetic polymer-peptide is water soluble, butattaches to a surface of a cell culture article under typical mammaliancell culture conditions, such as incubation in the medium at about 37°C. It will be understood that cell culture conditions do not includeexposure to radiation, such as UV radiation, at levels above backgroundor ambient levels.

The polymer-peptide may be added to, or may be a part of, cell culturemedium as an attachment supplement. Cells may be added to cell culturemedium containing the polymer-peptide, and the cell-seeded medium may bedisposed on, or contacted with, a cell culture article. Under cellculture conditions, e.g. incubation in the medium at about 37° C., thepolymer-peptide attaches to the surface of the cell culture article, andthe cells attach to the peptide of the polymer peptide. Thus, the cellsattach to the surface of the cell culture article via thepolymer-peptide.

In embodiments described herein, cell attachment to the surface of thecell culture article is enhanced by adding the polymer-peptide to themedium and contacting to an uncoated cell culture article, relative tocontacting cells in medium without the polymer-peptide to an articlethat has been pre-coated with the polymer-peptide.

Synthetic Polymer-Peptide

Any suitable water-soluble polymer having a conjugated polypeptide maybe employed as a cell culture medium attachment supplement, providedthat the polymer attaches to a surface of a cell culture article whenincubated in the medium under typical cell culture conditions. Inembodiments, the synthetic polymers and conjugated polypeptidesdescribed herein are soluble in cold (e.g., less than 20° C.) or roomtemperature (25° C.) water but become securely attached to a substratewhen exposed to typical cell culture conditions (e.g., about 37° C.). Inembodiments, the synthetic polymers and conjugated polypeptides becomesecurely attached to a substrate at temperatures around room temperature(e.g., at about 25° C.). The synthetic polymers and conjugatedpolypeptides may be modified to provide for substrate attachment at anydesired temperature. In embodiments, the polymers are free ofcrosslinkers or cross-link free, yet they attach to a cell culturesubstrate when contacted with the substrate in an aqueous medium, suchas cell culture medium. Attachment of the polymer-polypeptide to thesubstrate occurs without subjecting to levels of radiation, e.g. UVradiation, above typical background levels of radiation.

The polymers conjugated to polypeptide described herein may be watersoluble at room temperature or below. However, in embodiments, asubstantially similar polymer that is not conjugated to the polypeptideis not water soluble at room temperature or below. In such embodiments,the polypeptide serves to render the polymers conjugated to polypeptidewater soluble. In embodiments, the substantially similar polymer that isnot conjugated to the polypeptide is not water soluble at cell culturetemperatures, which is typically 37° C. but may be lower, such as roomtemperature (25° C.). It may also be desirable for the polymer to beswellable in water at 37° C. or a desired temperature for cell culture,to provide a suitable modulus for cell culture.

The polymers conjugated to the polypeptides may be formed by anysuitable process using any suitable monomers. In embodiments, the one ormore monomers used to form the polymer and the reaction mechanisms(e.g., step-growth polymerization or condensation polymerization, orchain polymerization or addition polymerization) used to form thepolymer are selected to form polymers with linear polymer backbones. Inembodiments, the one or more monomers used to form the polymer and thereaction mechanisms used to form the polymer are selected to formpolymers with branched polymer backbones. The branched polymers may befree of cross links. In embodiments, the one or more monomers used toform the polymer and the reaction mechanisms used to form the polymerare selected to form star. To form branched or star polymersmultifunctional monomers may be employed in combination withmonofunctional monomers. Suitable reaction schemes for forming branchedor dendritic or star polymers are discussed in, for example,Konkolewicz, et al., Dendritic and hyperbranched polymers frommacromolecular units: Elegant Approaches to the Synthesis of FunctionalPolymers, Macromolecules, 2011, 44:7067-7087. Of course any othersuitable techniques may be employed.

In many embodiments, the monomers used to form the polymers contain anethylenically unsaturated group, such as (meth)acrylates,(meth)acrylamides, maleimides, fumurates, vinylsulfones, or the like.The polymers may be homopolymers or copolymers. The monomers may bechosen such that the polymer is insoluble or less soluble in water at37° C., 25° C., etc., but is soluble in water in the range of 4° C. to25° C., 4° C. to 15° C. or 20° C., etc., when conjugated to thepolypeptide.

In various embodiments, a monomer employed is a (meth)acrylate monomerof Formula (I):

where A is H or methyl, and where B is H, C1-C6 straight or branchedchain alcohol or ether, or C1-C6 straight or branched chain alkylsubstituted with a carboxyl group (—COOH). In some embodiments, B isC1-C4 straight or branched chain alcohol. In some embodiments, B isstraight or branched chain C1-C3 substituted with a carboxyl group. Byway of example, 2-carboxyethyl methacrylate, 2-carboxyethyl acrylate,acrylic acid, methacrylic acid, hydroxypropyl methacrylate,2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, glycerolmethacrylate, hydroxypropyl acrylate, 4-hydroxybutyl acrylate, or thelike may be employed.

In various embodiments, a monomer employed is a (meth)acrylamide monomerof Formula (II):

where A is hydrogen or methyl, and where B is H, C1-C6 straight orbranched chain alcohol or ether, or C1-C6 straight or branched chainalkyl substituted with a carboxyl group (—COOH). In some embodiments, Bis straight or branched chain C1-C3 substituted with a carboxyl group.In some embodiments, B is C1-C4 straight or branched chain alcohol. Byway of example, 2-carboxyethyl acrylamide, acrylamidoglycolic acid,N-(hydroxymethyl)acrylamide, N-[Tris(hydroxymethyl)methyl]acrylamide,3-acryloylamino-1-propanol, N-acrylamido-ethoxyethanol, N-hydroxyethylacrylamide, or the like, may be used.

The monomer or monomers used to form the polymer may be selected toachieve a polymer having the desired characteristics (e.g., modulus,swellability, water solubility). For example, copolymers formed frommore than one monomer may have a greater degree of swellability thanhomopolymers formed from any one of the monomers alone. Generally,monomers having longer chain alkyl groups will tend to render thepolymer too water insoluble for the conjugated polypeptide to make thepolymer-polypeptide water soluble at appropriate temperatures.Additionally, monomers having moieties that favor hydrogen bonding orthat are charged at selected pH levels may tend to make the polymer morewater soluble. One of skill in the art will readily be able to selectthe appropriate monomers and monomer ratios for preparing polymershaving desired characteristics.

Once the appropriate monomers in the appropriate amounts are selected,the polymer may be formed via polymerization reaction. In addition tothe monomers that form the polymer, a composition may include one ormore additional compounds such as surfactants, wetting agents,photoinitiators, thermal initiators, catalysts, and activators.

Any suitable polymerization initiator may be employed. One of skill inthe art will readily be able to select a suitable initiator, e.g. aradical initiator or a cationic initiator, suitable for use with themonomers. In various embodiments, UV light is used to generate freeradical monomers to initiate chain polymerization. Examples ofpolymerization initiators include organic peroxides, azo compounds,quinones, nitroso compounds, acyl halides, hydrazones, mercaptocompounds, pyrylium compounds, imidazoles, chlorotriazines, benzoin,benzoin alkyl ethers, diketones, phenones, or mixtures thereof. Examplesof suitable commercially available, ultraviolet-activated and visiblelight-activated photoinitiators have tradenames such as IRGACURE 651,IRGACURE 184, IRGACURE 369, IRGACURE 819, DAROCUR 4265 and DAROCUR 1173commercially available from Ciba Specialty Chemicals, Tarrytown, N.Y.and LUCIRIN TPO and LUCIRIN TPO-L commercially available from BASF(Charlotte, N.C.)

A photosensitizer may also be included in a suitable initiator system.Representative photosensitizers have carbonyl groups or tertiary aminogroups or mixtures thereof. Photosensitizers having a carbonyl groupsinclude benzophenone, acetophenone, benzil, benzaldehyde,o-chlorobenzaldehyde, xanthone, thioxanthone, 9,10-anthraquinone, andother aromatic ketones. Photosensitizers having tertiary amines includemethyldiethanolamine, ethyldiethanolamine, triethanolamine,phenylmethyl-ethanolamine, and dimethylaminoethylbenzoate. Commerciallyavailable photosensitizers include QUANTICURE ITX, QUANTICURE QTX,QUANTICURE PTX, QUANTICURE EPD from Biddle Sawyer Corp.

In general, the amount of photosensitizer or photoinitiator system mayvary from about 0.01 to 10% by weight.

Examples of cationic initiators that may be employed include salts ofonium cations, such as arylsulfonium salts, as well as organometallicsalts such as ion arene systems.

Examples of free radical initiators that may be employed includeazo-type initiators such as 2-2′-azobis(dimethyl-valeronitrile),azobis(isobutyronitrile), azobis(cyclohexane-nitrite),azobis(methyl-butyronitrile), and the like, peroxide initiators such asbenzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide,isopropyl peroxy-carbonate,2,5-dienethyl-2,5-bas(2-ethylhexanoyl-peroxy)hexane, di-tert-butylperoxide, cumene hydroperoxide, dichlorobenzoyl peroxide, potassiumpersulfate, ammonium persulfate, sodium bisulfate, combination ofpotassium persulfate, sodium bisulfate and the like, and mixturesthereof. Of course, any other suitable free radical initiators may beemployed. An effective quantity of an initiator is generally within therange of from about 0.1 percent to about 15 percent by weight of thereaction mixture, such as from 0.1 percent to about 10 percent by weightor from about 0.1 percent to about 8 percent by weight of the reactionmixture.

In various embodiments, one or more monomers are diluted prior toundergoing polymerization.

The polymer resulting from the polymerization reaction may have anysuitable molecular weight. In various embodiments, the polymer has anaverage molecular weight (Mw) of between 10,000 and 1000,000 Daltons,such as between 10,000 and 250,000 Daltons. One of skill in the art willunderstand that the amount of initiator, reaction time, reactiontemperature, and the like may be varied to adjust the molecular weightof the resulting polymer.

(Meth)acrylate monomers, (meth)acrylamide monomers, or other suitablemonomers may be synthesized as known in the art or obtained from acommercial vendor, such as Polysciences, Inc., Sigma Aldrich, Inc., andSartomer, Inc.

The polypeptide may be conjugated to the polymer in any suitable manner.In some embodiments a monomer is derivatized to include the polypeptideand, thus, the polypeptide is incorporated into the polymer as it isbeing formed. In some embodiments, the polypeptide is grafted to thepolymer after the polymer is formed.

Referring now to FIGS. 1-2 examples of reaction schemes forincorporating a polypeptide into a polymer as it is being formed isshown. In FIG. 1, a vitronectin polypeptide (VN) is conjugated tomethacrylate (MAA) via a repeating polyethylene glycol (PEG₄) spacer. Ahomopolymer is produced by polymerizing the monomer MAA that isconjugated to the polypeptide (VN) under appropriate conditions. In thedepicted embodiment, ethanol is the solvent,2,2′-Azodi(2-methylbutyronitrile) (AMBN) is the thermal initiator, thereaction temperature is 68° C., and the reaction is carried out underargon.

A monomer may be derivatized to include a polypeptide using any suitableprocess, such as described in Example 1 presented herein. Well knownprocesses for preparing polypeptide-monomers are described inUS2007/0190036, published on Aug. 16, 2007, naming Kizilel, S., et al.as inventors. Of course, other methods for derivatizing a monomer with apolypeptide may be used.

In the embodiment depicted in FIG. 2, a copolymer is formed from2-hydroxyethylmethacrylate (HEMA) and MAA-PEG₄-VN under similar reactionconditions to those described with regard to FIG. 1 above. The use ofmultiple monomers to produce the polymer allows one to more readily tunethe properties of the resulting polymer as desired, regardless ofwhether the polypeptide is incorporated into the polymer as the polymeris formed.

In embodiments, a peptide monomer peptide is described by formula 1:R_(m)—S_(p)—C_(ap),  Formula 1:

where, R is a polymerization moiety, “m” is an interger greater than orequal to 1, S_(p) is an optional spacer, and C_(ap) is a cell adhesivepolypeptide (e.g., as described below). R may be an α, β-unsaturatedgroup or ethylenically unsaturated group which includes acrylate,methacrylate, acrylamide, methyacrylamide, maleimide or a fumarate,which is capable of polymerizing in the presence of an external energysource. In embodiments, the functionalized peptide has a polymerizationmoiety R which may be a photopolymerizable moiety or a thermalpolymerizable moiety.

In embodiments, S_(p) may be a polyalkylene oxide including for examplepolyethylene glycol (PEG) or polypropylene glycol (PPG) which arerepresented by the formula (O—CH₂CHR′)_(m2) where R′ is H or CH₃ and m2is an integer from 0 to 200, such as 0 to 100 or 0 to 20. The spacer maybe a hydrophilic spacer, for example, polyethelene oxide (PEO). Inembodiments, the spacer is PEG₄. In embodiments, relatively short chainsof polyalkylene oxide are desirable. For example, in embodiments, S_(p)may be PEG₂, PEG₄, PEG₆, PEG₈, PEG₁₀, PEG₁₂ or PPG₂, PPG₄, PPG₆, PPG₈,PPG₁₀, PPG₁₂ or PPG₂₀. In embodiments, the spacer is a polyethyleneoxide with 20 or fewer repeating units (i.e. PEG₄, PEG₆, PEG₈, PEG₁₀,PEG₁₂, PEG₁₄, PEG₁₆, PEG₁₈ or PEG₂₀). In embodiments S_(p) is PPG or PEGhaving a functional group. For example, the PEG or PPG spacer may have amaleimide, thiol, amine, silane, aldehyde, epoxide, isocyanate, acrylateor carboxyl group. In embodiments the PEG spacer is a Jeffamine, a PEGhaving an amine functional group. In additional embodiments, the PEG orPPG may be branched. For example the branched PEG or PPO may be aY-branched or star-PEG or PPG. In embodiments these branched PEG or PPOspacers may allow multiple peptides to be conjugated to a base materialthrough a single functional peptide.

Once a cell culture surface is formed (discussed below in more detail),the spacer may act to extend the peptide (C_(ap)) away from the cellculture surface, making the peptide more accessible to cells in culture,and improving the efficiency of the surface for cell culture. Inaddition, hydrophilic spacers may act to repel proteins, preventingnon-specific absorption of cells or proteins to the functionalizedpeptide. In embodiments, the use of a cell adhesive peptide with aspacer such as PEO (polyethylene oxide) in preparing cell culturearticles allows for the preparation of such articles using a loweroverall concentration of adhesive peptide.

In embodiments, S_(p) may be an amino acid Xaa_(n) where Xaa isindependently any amino acid and n is an integer from 0 to 30, from 0 to10, from 0 to 6 or from 0 to 3. For example, in embodiments, S_(p) maybe an amino acid Xaa_(n) where Xaa is G and where n=1 to 20, or S_(p)may be an amino acid Xaa_(n) where Xaa is K and n=1 to 20, or S_(p) maybe an amino acid Xaa_(n) where Xaa is D and n=1 to 20, or S_(p) may bean amino acid Xaa_(n) where Xaa is E and n=1 to 20. In embodiment,spacer S_(p) may be a three amino acid sequence such as LysGlyGly orLysTyrGly. In embodiments, Xaa_(n) is a series of the same amino acid.In embodiments, the spacer S_(p) may be combinations of Xaa_(n) andpolyethylene or polypropylene oxide. Xaa_(n) may comprise a hydrophilicamino acid such as lysine, glycine, glutamic acid, aspartic acid orarginine amino acid. In embodiments, Xaa_(n) may have a terminal lysineor arginine. Or, in embodiments, the spacer S_(p) may comprisepolyethylene oxide spacer and amino acid spacer in any combination. Inembodiments, S_(p) may be a hydrophobic spacer such as palmitic acid,stearic acid, lauric acid or hexaethylene diamine. In embodiments, S_(p)may be carboxyethyl methacrylate.

The polymerization moiety may attach to the spacer, S_(p), in anysuitable manner such as through polyethylene oxide, through the sidechain of an amino acid such as lysine, at the N-terminus of the aminoacid, or the like. Amino acid Xaa_(n) may be acetylated and/or amidatedto protect it from degradation. However, if Xaa_(n) is acetylated, thepolymerization moiety cannot be bound to Xaa_(n) through the N-terminusof the amino acid. For example, a methacrylic acid may be bound to alysine amino acid through the side chain of the lysine amino acid whereS_(p) is Xaa_(n), Xaa is lysine, n=1, and R_(m) is methacrylic acid.

In embodiments, the spacer S_(p) is Xaa_(n) and Xaa_(n) has a terminallysine. In embodiments, Xaa_(n) may be bound to a polymerization moietyR_(m). For example, Xaa_(n) may be (MAA)LysGlyGly or (MAA)LysTyrGly,where MAA is the polymerization moiety methacrylic acid (MAA) bound toXaa_(n) through the side chain of the terminal lysine amino acid. Inadditional embodiments, the polymerization moiety may be bound to theN-terminus of the Xaa_(n) amino acid or amino acid chain, if theN-terminus is not acetylated. Each functionalized peptide has at leastone polymerization moiety, and may have more than one.

In various embodiments, a polypeptide is grafted to a polymer that hasalready been formed. Preferably, polypeptide includes an amino acidcapable of conjugating to a pendant reactive group of the polymer.Examples of reactive groups that the polymer may have for reaction witha polypeptide include maleimide, glycidyl, isocyanate, isothiocyante,activated esters, activated carbonates, anhydride, and the like. By wayof example, any native or biomimetic amino acid having functionalitythat enables nucleophilic addition; e.g. via amide bond formation, maybe included in polypeptide for purposes of conjugating to thepolypeptide having a suitable reactive group. Lysine, homolysine,ornithine, diaminoproprionic acid, and diaminobutanoic acid are examplesof amino acids having suitable properties for conjugation to a reactivegroup of the polymer, such as carboxyl group. In addition, theN-terminal alpha amine of a polypeptide may be used to conjugate to thecarboxyl group, if the N-terminal amine is not capped. In variousembodiments, the amino acid of polypeptide that conjugates with thepolymer is at the carboxy terminal position or the amino terminalposition of the polypeptide.

A polypeptide may be conjugated to the polymer via any suitabletechnique. A polypeptide may be conjugated to a polymer via an aminoterminal amino acid, a carboxy terminal amino acid, or an internal aminoacid. One suitable technique involves1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride(EDC)/N-hydroxysuccinimide (NHS) chemistry, as generally known in theart. EDC and NHS or N-hydroxysulfosuccinimide (sulfo-NHS) can react withfree carboxyl groups of the polymer to produce amine reactive NHSesters. EDC reacts with a carboxyl group of the polymer to produce anamine-reactive O-acylisourea intermediate that is susceptible tohydrolysis. The addition of NHS or sulfo-NHS stabilizes theamine-reactive O-acylisourea intermediate by converting it to an aminereactive NHS or sulfo-NHS ester, allowing for a two-step procedure.Following activation of the polymer, the polypeptide may then be addedand the terminal amine of the polypeptide can react with the aminereactive ester to form a stable amide bond, thus conjugating thepolypeptide to the polymer layer. When EDC/NHS chemistry is employed toconjugate a polypeptide to the polymer, the N-terminal amino acid ispreferably an amine containing amino acid such as lysine, ornithine,diaminobutyric acid, or diaminoproprionic acid. Of course, anyacceptable nucleophile may be employed, such as hydroxylamines,hydrazines, hydroxyls, and the like.

EDC/NHS chemistry results in a zero length crosslinking of polypeptideto polymer. Linkers or spacers, such as poly(ethylene glycol) linkers(e.g., available from Quanta BioDesign, Ltd.) with a terminal amine maybe added to the N-terminal amino acid of polypeptide. When adding alinker to the N-terminal amino acid, the linker is preferably aN-PG-amido-PEG_(X)-acid where PG is a protecting group such as the Fmocgroup, the BOC group, the CBZ group or any other group amenable topeptide synthesis and X is 2, 4, 6, 8, 12, 24 or any other discrete PEGwhich may be available. Of course, any other suitable mechanism forgrafting the polypeptide to the polymer may be used.

Regardless of how the polypeptide is conjugated to the polymer; e.g.,via incorporation of a derivitized monomer conjugated to the polypeptideor via grafting, the ratio of monomers to which the polypeptide isattached or is to be attached (peptide-monomer) to monomers to which nopolypeptide is attached or is to be attached (nonpeptide-monomer) may bevaried to achieve desired properties, such as swellability, watersolubility, modulus, and the like. In embodiments, the molar ratio ofpeptide monomer to nonpeptide monomer is from about 1:1 to about 1:50,such as from about 1:5 and 1:20, about 1:10, about 1:9 or the like.

In embodiments, the polypeptide is conjugated to the polymer via alinker or spacer. A linker or spacer, such as a repeating poly(ethyleneglycol) linker, or any other suitable linker, may be used to increasedistance from polypeptide to surface of polymer. The linker may be ofany suitable length. For example, if the linker is a repeatingpoly(ethylene glycol) linker, the linker may contain between 2 and 10repeating ethylene glycol units. In some embodiments, the linker is arepeating poly(ethylene glycol) linker having about 4 repeating ethyleneglycol units. All, some, or none of the polypeptides may be conjugatedto a polymer via linkers. Other potential linkers that may be employedinclude polypeptide linkers such as poly(glycine) or poly(β-alanine).

A linker may serve to provide better accessibility of the polypeptide tocells when used in cell culture. In addition, the use of a linker inembodiments where the polypeptide is conjugated to a monomer, theefficiency of polymerization of the monomer into a homopolymer orcopolymer may be increased.

The polypeptide may be cyclized or include a cyclic portion. Anysuitable method for forming cyclic polypeptide may be employed. Forexample, an amide linkage may be created by cyclizing the free aminofunctionality on an appropriate amino-acid side chain and a freecarboxyl group of an appropriate amino acid side chain. Also, adisulfide linkage may be created between free sulfydryl groups of sidechains appropriate amino acids in the peptide sequence. Any suitabletechnique may be employed to form cyclic polypeptides (or portionsthereof). By way of example, methods described in, e.g., WO1989005150may be employed to form cyclic polypeptides. Head-to-tail cyclicpolypeptides, where the polypeptides have an amide bond between thecarboxy terminus and the amino terminus may be employed. An alternativeto the disulfide bond would be a diselenide bond using twoselenocysteines or mixed selenide/sulfide bond, e.g., as described inKoide et al, 1993, Chem. Pharm. Bull. 41(3):502-6; Koide et al., 1993,Chem. Pharm. Bull. 41(9):1596-1600; or Besse and Moroder, 1997, Journalof Peptide Science, vol. 3, 442-453.

Polypeptides may be synthesized as known in the art (or alternativelyproduced through molecular biological techniques) or obtained from acommercial vendor, such as American Peptide Company, CEM Corporation, orGenScript Corporation. Linkers may be synthesized as known in the art orobtained from a commercial vendor, such as discrete polyethylene glycol(dPEG) linkers available from Quanta BioDesign, Ltd.

In various embodiments, the polypeptide, or a portion thereof, has celladhesive activity; i.e., when the polypeptide is conjugated to thepolymer, the polypeptide allows a cell to adhere to the surface of thepeptide-containing polymer. By way of example, the polypeptide mayinclude an amino sequence, or a cell adhesive portion thereof,recognized by proteins from the integrin family or leading to aninteraction with cellular molecules able to sustain cell adhesion. Forexample, the polypeptide may include an amino acid sequence derived fromcollagen, keratin, gelatin, fibronectin, vitronectin, laminin, bonesialoprotein (BSP), or the like, or portions thereof. In variousembodiments, polypeptide includes an amino acid sequence of ArgGlyAsp(RGD).

Examples of peptides that may be used in embodiments herein are listedin Table 1.

TABLE 1 Non-limiting examples of polypeptides Sequence SourceKGGGQKCIVQTTSWSQCSKS Cyr61 res 224-240 (SEQ ID NO: 1)GGGQKCIVQTTSWSQCSKS Cyr61 res 224-240 (SEQ ID NO: 2)KYGLALERKDHSG (SEQ ID NO: 3) TSP1 res 87-96 YGLALERKDHSG (SEQ ID NO: 4)TSP1 res 87-96 KGGSINNNRWHSIYITRFGNMGS mLMα1 res (SEQ ID NO: 5)2179-2198 GGSINNNRWHSIYITRFGNMGS mLMα1 res (SEQ ID NO: 6) 2179-2198KGGTWYKIAFQRNRK (SEQ ID NO: 7) mLMα1 res 2370-2381GGTWYKIAFQRNRK (SEQ ID NO: 8) mLMα1 res 2370-2381KGGTSIKIRGTYSER (SEQ ID NO: 9) mLMγ1 res 650-261GGTSIKIRGTYSER (SEQ ID NO: 10) mLMγ1 res 650-261 KYGTDIRVTLNRLNTFmLMγ1 res 245-257 (SEQ ID NO: 11) YGTDIRVTLNRLNTF (SEQ ID NO: 12)mLMγ1 res 245-257 KYGSETTVKYIFRLHE mLMγ1 res 615-627 (SEQ ID NO: 13)YGSETTVKYIFRLHE (SEQ ID NO: 14) mLMγ1 res 615-627KYGKAFDITYVRLKF (SEQ ID NO: 15) mLMγ1 res 139-150YGKAFDITYVRLKF (SEQ ID NO: 16) mLMγ1 res 139-150KYGAASIKVAVSADR (SEQ ID NO: 17) mLMα1 res2122-2132YGAASIKVAVSADR (SEQ ID NO: 18) mLMα1 res2122-2132CGGNGEPRGDTYRAY (SEQ ID NO: 19) BSP GGNGEPRGDTYRAY (SEQ ID NO: 20) BSPCGGNGEPRGDTRAY (SEQ ID NO: 21) BSP-Y GGNGEPRGDTRAY (SEQ ID NO: 22) BSP-YKYGRKRLQVQLSIRT (SEQ ID NO: 23) mLMα1 res 2719-2730YGRKRLQVQLSIRT (SEQ ID NO: 24) mLMα1 res 2719-2730KGGRNIAEIIKDI (SEQ ID NO: 25) LMβ1 GGRNIAEIIKDI (SEQ ID NO: 26) LMβ1KGGPQVTRGDVFTMP (SEQ ID NO: 27) VN GGPQVTRGDVFTMP (SEQ ID NO: 28) VNGRGDSPK (SEQ ID NO: 29) Short FN KGGAVTGRGDSPASS (SEQ ID NO: 30) Long FNGGAVTGRGDSPASS (SEQ ID NO: 31) Long FN Yaa₁PQVTRGNVFTMP VN(SEQ ID NO: 32) RGDYK (SEQ ID NO: 33) RGD

For any of the polypeptides discussed herein, it will be understood thata conservative amino acid may be substituted for a specificallyidentified or known amino acid. A “conservative amino acid”, as usedherein, refers to an amino acid that is functionally similar to a secondamino acid. Such amino acids may be substituted for each other in apolypeptide with a minimal disturbance to the structure or function ofthe polypeptide according to well-known techniques. The following fivegroups each contain amino acids that are conservative substitutions forone another: Aliphatic: Glycine (G), Alanine (A), Valine (V), Leucine(L), Isoleucine (I); Aromatic: Phenylalanine (F), Tyrosine (Y),Tryptophan (W); Sulfur-containing: Methionine (M), Cysteine (C); Basic:Arginine (R), Lysine (K), Histidine (H); Acidic: Aspartic acid (D),Glutamic acid (E), Asparagine (N), Glutamine (Q).

One or more polypeptide may be conjugated to a polymer, whether graftedor incorporated during polymer formation, in any suitable amount.Preferably, weigh percentage of the polypeptide is sufficiently high torender the polymer conjugated to the polymer water soluble. In variousembodiments, the weight percentage of the polypeptide relative to thepolymer conjugated to the polypeptide is 10% or greater, 20% or greater,40% or greater, 60% or greater, or the like. Such weight percentageshave been determined to achieve good water solubility, immobilizationefficiency and acceptable cell adhesion for polypeptides having amolecular weight of 1500 Daltons or higher.

Polymers as described herein provide a synthetic surface to which anysuitable adhesion polypeptide or combinations of polypeptides may beconjugated, providing an alternative to biological substrates or serumthat have unknown components. In current cell culture practice, it isknown that some cell types require the presence of a biologicalpolypeptide or combination of peptides on the culture surface for thecells to adhere to the surface and be sustainably cultured. For example,HepG2/C3A hepatocyte cells can attach to plastic culture ware in thepresence of serum. It is also known that serum can provide polypeptidesthat can adhere to plastic culture ware to provide a surface to whichcertain cells can attach. However, biologically-derived substrates andserum contain unknown components. For cells where the particularcomponent or combination of components (peptides) of serum orbiologically-derived substrates that cause cell attachment are known,those known polypeptides can be synthesized and applied to a polymer asdescribed herein to allow the cells to be cultured on a syntheticsurface having no or very few components of unknown origin orcomposition.

Cell Culture Medium Composition

The polymer conjugated to the polypeptide may be dissolved in an aqueoussolution for use in coating cell culture articles or culturing cells. Inembodiments, the aqueous solution is free, or substantially free, oforganic solvents. It will be understood that some minor amounts oforganic solvents may be present in the aqueous solution, for example asa result some organic solvent remaining in the polymer afterpolymerization. As used herein, “substantially free,” as it relates toan organic solvent in an aqueous solution, means that the aqueoussolution comprises less than 2% of the organic solvent by weight. Inmany embodiments, the aqueous solution contains less than 1%, less than0.5%, less that 0.2% or less that 0.1% of an organic solvent. Examplesof organic solvents from which the aqueous solution is free includemethanol, ethanol, butanol, propanol, octanol, hexane, heptane, acetone,acetyl acetate, ethyl acetate, dimethylformamide (DMF),dimethylsulfoxide (DMSO), and the like.

The polymer conjugated to the polypeptide may be dissolved in theaqueous solution at any suitable concentration for purposes of coatingor culture. For example, the aqueous solution may contain between 0.001mg/ml and 1 mg/ml of the polymer conjugated to the polypeptide, such asbetween 0.003 mg/ml and 0.05 mg/ml of the polymer conjugated to thepolypeptide.

In embodiments, the aqueous solution is a cell culture medium solution,meaning that the solution is configured to support the culture of cells,such as mammalian cells. In embodiments, the cells are stem cells, suchas human embryonic stem cells or human mesenchymal stem cells. The cellculture medium solution may have a pH of between about 7 and about 8,such as between about 7.2 and 7.5, which may be buffered by a pH buffer,such as phosphate buffer, citrate buffer, or the like. The cell culturemedium solution may include any components suitable for cell culture,such as glucose, amino acids, vitamins, inorganic salts or the like.Cell culture constituents and concentrations are known in the art. See,for example, Burgener A, Butler. “Medium Development”. In Cell CultureTechnology For Pharmaceutical and Cell-Based Therapies. Edited by OzturkS S and Hu W S. 2006. In embodiments, the cell culture medium includesd-glucose.

Examples of various components that may be included in a cell culturemedium and concentrations of the components in the medium are providedbelow. By way of example, the cell culture medium may comprise fromabout 1 mM d-glucose to about 50 mM d-glucose, such as from about 2 mMto about 30 mM d-glucose. Examples of amino acids that may be includedin the cell culture medium include 1-arginine, 1-cystine, 1-histidine,1-isoleucine, 1-leucine, 1-lysine, 1-methionine, 1-phenylaline,1-threonine, 1-tryptophan, 1-tyrosine, 1-valine or the like. The aminoacids may be present at any suitable concentration, such as from about1×10⁻³ mM to about 20 mM. It will be understood that the concentrationof the amino acid may vary depending on the amino acid. Inorganic saltsmay be included in the cell culture medium at appropriateconcentrations. Examples of suitable inorganic salts include calciumchloride, calcium nitrate, cupric sulfate, ferric nitrate, ferroussulfate, potassium chloride, magnesium chloride, magnesium sulfate,sodium chloride, sodium bicarbonate, sodium phosphate, and the like.

In embodiments, the polymer-polypeptide is dissolved in a commerciallyavailable cell culture medium, such as DMEM (Dulbecco's Modified EagleMedium) such as available from GIBCO; StemPro® a fully defined, serum-and feeder-free medium (SFM) specially formulated for the growth andexpansion of human embryonic stem cells (hESCs), available fromInvitrogen; mTeSR™ 1 maintenance media for human embryonic stem cells,available from StemCell Technologies, Inc.; MesenCult®-XF medium, whichis a standardized, xeno-free, serum-free medium for the culture of humanmesenchymal stem cells, available from StemCell Technologies Inc.; orthe like.

In embodiments, the cell culture medium is a chemically-defined medium.Because all components of chemically-defined media have a known chemicalstructure or are formed from components of known structure (e.g.,synthetic polymers formed from monomers of known structure), variabilityin culture conditions and thus cell response can be reduced, increasingreproducibility. In addition, the possibility of contamination isreduced. Further, the ability to scale up is made easier due, at leastin part, to the factors discussed above. Chemically defined cell culturemedia are commercially available from Invitrogen (InvitrogenCorporation, 1600 Faraday Avenue, PO Box 6482, Carlsbad, Calif. 92008)as StemPro® a fully defined, serum- and feeder-free medium (SFM)specially formulated for the growth and expansion of human embryonicstem cells (hESCs) and StemCell Technologies, Inc. as mTeSR™1maintenance media for human embryonic stem cells. MesenCult®-XF Mediumis another example of a chemically-defined medium available fromSTEMCELL Technologies Inc.

In embodiments, the cell culture medium is conditioned medium to which apolymer-polypeptide has been added.

In embodiments, the aqueous solution, such as cell culture mediumsolution, is free or substantially free of cross-linking agents. As usedherein, “cross-linking agent” refers to an agent capable of inducingcross-linking in, or capable of cross-linking, the polymer portion ofthe polymer-polypeptide. As used herein, “substantially free” as itrelates to cross-linking agents, means that no appreciable crosslinkingoccurs in the polymer as a result of the presence of trace amounts of acrosslinking agent. Examples of cross-linkers that the polymer portionis substantially free from include well known crosslinking agentsinclude homo-multifunctional or hetero-multifunctional crosslinkingagent as those described in “Bioconjugate Techniques, Second Edition byGreg T. Hermanson”. In embodiments, the composition is also“substantially free” of multifunctional oligomers and polymers thatcould lead to formation of interpenetrated network orsemi-interpenetrated network.

The cell culture medium containing the polymer having conjugatedpolypeptide may be sterilized in any suitable manner. In embodiment, thepolymer-polypeptide is sterilized via gamma radiation; e.g. as a drypowder, and added to sterilized cell culture medium using aseptictechnique. Gamma or e-beam radiation, rather than filter sterilizationas used with naturally occurring or animal derived extracellular matrixproteins, may be beneficially used with the syntheticpolymer-polypeptides described herein. Of course, filter sterilizationmay be employed if desired.

The cell culture medium containing the polymer having conjugatedpolypeptide may be stored at room temperature (25° C.) or below to keepthe polymer-polypeptide in solution. By way of example, the medium maybe refrigerated (about 5° C.) for storage. Refrigeration may also serveto prolong the shelf-life of the medium.

Coating Process

The polymer conjugated to the polypeptide may be coated onto a cellculture article in any suitable manner. Generally, an aqueous solution,such as a cell culture medium, containing the polymer conjugated to thepolypeptide, as described above, is disposed on a surface of the cellculture article. The polymer conjugated to the polypeptide is thenincubated with the cell culture article in the aqueous solution undercell culture conditions, such as at 37° C., about 25° C. or the like,until the polymer conjugated to the polypeptide attaches to the surfaceof the cell culture article. In embodiments, the attachment processbegins immediately, within seconds or minutes.

While it is possible that the polymer covalently attaches to the surfaceof the article, the polymer will typically be attached to the articlevia non covalent interactions. Examples of non-covalent interactionsthat may attach the polymer with the substrate include chemicaladsorption, hydrogen bonding, surface interpenetration, ionic bonding,van der Waals forces, hydrophobic interactions, dipole-dipoleinteractions, mechanical interlocking, and combinations thereof.

Preferably, the polymer attaches to and coats the surface of the articleduring cell culture conditions, such as in the presence of cell culturemedia at 37° C. Because the polymer-polypeptide is stable in, andcompatible with, cell culture medium, it is acceptable for some of thepolymer-polypeptide to remain in the medium or for equilibrium betweenattached and unattached polymer-polypeptide to exist. Preferably uponreplenishment of medium; e.g., removal of used medium and replacementwith new medium (e.g., without polymer-polypeptide), the attachedpolymer-polypeptide remains attached to the substrate. In embodiments,90% or more, such as 95% or more or 99% or more, of the previouslyattached polymer-polypeptide remains attached during medium replacement.In embodiments, replacement medium may include an appropriateconcentration of polymer-polypeptide to maintain a desired equilibriumpolymer-peptide coating on substrate on the substrate.

Without intending to be bound to any particular theory, it is believedthat the high percentage of polypeptide relative to the polymer aids inthe surprising adsorption of the polymer on appropriate substrates froman aqueous solution and its non-solubility in water after adsorption.The high polypeptide content may lead to a high density of hydrogenbonding between polypeptides, inducing physical crosslinking oraggregation, which is a behaviour similar to natural occurring proteins.It is also well-known that some specific polypeptides are soluble inaqueous solution below their transition temperature, but theyhydrophobically collapse and aggregate when the temperature is raisedabove the transition temperature. Such hydrophobic collapse may play arole in adsorption of polymers conjugated with polypeptides that aresubjected to cell culture conditions, such as 37° C.

The surface of the cell culture article to which the polymer conjugatedto the polypeptide is coated may be formed of any suitable material. Forexample, the surface of the cell culture article may be formed from aceramic substance, a glass, a plastic, a polymer or co-polymer, anycombinations thereof, or a coating of one material on another. Such basematerials include glass materials such as soda-lime glass, pyrex glass,vycor glass, quartz glass; silicon; plastics or polymers, includingdendritic polymers, such as poly(vinyl chloride), poly(vinyl alcohol),poly(methyl methacrylate), poly(vinyl acetate-co-maleic anhydride),poly(dimethylsiloxane) monomethacrylate, cyclic olefin polymers,fluorocarbon polymers, polystyrenes, polypropylene, polyethyleneimine;copolymers such as poly(vinyl acetate-co-maleic anhydride),poly(styrene-co-maleic anhydride), poly(ethylene-co-acrylic acid) orderivatives of these or the like.

In embodiments, the surface of the cell culture article to which thepolymer-polypeptide attaches has a water contact angle (sessile dropmeasurement) of from about 0 to about 100, such as from about 0 to about50, from about 0 to about 30, from about 12° to about 85°, from about25° to about 70°, from about 30° to about 60°, or the like. It will beunderstood that substrates may be treated so that they exhibit anappropriate contact angle. For example, the substrate may be coronatreated or plasma treated. Examples of vacuum or atmospheric pressureplasma include RF and microwave plasmas both primary and secondary,dielectric barrier discharge, and corona discharge generated inmolecular or mixed gases including air, oxygen, nitrogen, argon, carbondioxide, nitrous oxide, or water vapor. By way of example, plasmatreated polystyrene, such as TCT polystyrene or CellBIND® treatedpolystyrene provide good substrates for polymer-polypeptide attachment.Naturally occurring animal-derived biological adhesive proteins alsoexhibit good binding to such surfaces. Accordingly, surfaces to whichnaturally occurring proteins readily attach may also provide goodsubstrates for polymer-polypeptide attachment.

Cell Culture Article

A polymer conjugated to a polypeptide as described herein may beattached to the surface of any suitable cell culture article, such assingle and multi-well plates, such as 6, 12, 96, 384, and 1536 wellplates, jars, petri dishes, flasks, beakers, plates, microcarriers suchas glass or polymer beads, roller bottles, slides, such as chambered andmultichambered culture slides, tubes, cover slips, bags, membranes,hollow fibers, beads and microcarriers, cups, spinner bottles, perfusionchambers, bioreactors, CellSTACK® and fermenters.

Referring to FIG. 3A, a schematic diagram of a side view of an article100 for culturing cells is shown. The article 100 includes a basematerial substrate 10 having a surface 15. A polymer 20 conjugated to apolypeptide 70 is disposed on the surface 15 of the base material 10. Asdepicted, the polypeptide 70 may be conjugated or covalently bound tothe polymer 20 directly or indirectly via linker 80 as described above.While not shown, it will be understood that the polymer 20 conjugated tothe polypeptide 70 may be disposed on a portion of base material 10. Thebase material 10 may be any material suitable for culturing cells, suchas those described above.

As shown in FIG. 3B, an intermediate layer 30 may be disposed betweensurface 15 of base material 10 and the coated polymer 20 conjugated tothe polypeptide 70. Intermediate layer 30 may be configured to improvebinding of the coated polymer 20 conjugated to the polypeptide 70 to thesubstrate 10, to facilitate spreading of the aqueous solution containingthe polymer conjugated to the polypeptide, to render portions of thesurface 10 that are uncoated cytophobic to encourage cell growth oncoated areas, to provide topographical features if desired through, forexample, patterned printing, or the like. For example, if substrate 10is a glass substrate, it may be desirable to treat a surface of theglass substrate with an epoxy coating or a silane coating. For variouspolymer base materials 10 it may be desirable to provide an intermediatelayer 30 of polyamide, polyimide, polypropylene, polyethylene, orpolyacrylate. While not shown, it will be understood that the coatedpolymer 20 conjugated to the polypeptide 70 may be disposed on a portionof intermediate layer 30. It will be further understood thatintermediate layer 30 may be disposed on a portion of base material 10.

Article 100, in numerous embodiments, is cell culture ware having awell, such as a Petri dish, a multi-well plate, a flask, a beaker orother container having a well. Referring now to FIG. 4, article 100formed from base material 10 may include one or more wells 50. Well 50includes a sidewall 55 and a surface 15.

Referring to FIG. 4B-C, a polymer 20 conjugated to a polypeptide 70 maybe disposed on surface 15 or sidewalls 55 (or, as discussed above withregard to FIG. 1 one or more intermediate layer 30 may be disposedbetween surface 15 or sidewall 55 and coated polymer 20 conjugated tothe polypeptide 70) or a portion thereof. As shown in FIG. 4C, sidewalls55 may be coated with polymer 20 conjugated to polypeptide 70.

In various embodiments, surface 15 of base material 10 is treated,either physically or chemically, to impart a desirable property orcharacteristic to the surface 15. For example, and as discussed above,surface 15 may be corona treated or plasma treated.

In embodiments, the coated polymer 20 conjugated to the polypeptide 70,whether disposed on an intermediate layer 30 or base material 10,uniformly coats the underlying substrate. By “uniformly coated”, it ismeant that the layer 20 in a given area, for example a surface of a wellof a culture plate, completely coats the area at a thickness of about 5nm or greater. While the thickness of a uniformly coated surface mayvary across the surface, there are no areas of the uniformly coatedsurfaces through which the underlying layer (either intermediate layer30 or base material 10) is exposed. Cell responses across non-uniformsurfaces tend to be more variable than cell responses across uniformsurfaces.

In various embodiments, article 100 includes a uniformly coated layer 20having a surface 25 with an area greater than about 5 mm². When the areaof the surface 15 is too small, reliable cell responses may not bereadily observable because some cells, such as human embryonic stemcells, are seeded as colonies or clusters of cells (e.g., having adiameter of about 0.5 mm) and adequate surface is desirable to ensureattachment of sufficient numbers of colonies to produce a quantitativecell response. In numerous embodiments, an article 100 has a well 50having a uniformly coated surface 15, where the surface 15 has an areagreater than about 0.1 cm², greater than about 0.3 cm², greater thanabout 0.9 cm², or greater than about 1 cm².

Incubating Cells on Synthetic Polymer Containing Conjugated Polypeptide

A cell culture article having a polymer containing a conjugatedpolypeptide as described above may be seeded with cells. In embodiments,the cells are introduced into cell culture medium that includes thepolymer-polypeptide as discussed above. During the cell culture process,the polymer conjugated to the polypeptide coats a surface of the cellculture article.

Without intending to be bound by theory, it is believed that cell-cellinteraction may be enhanced by including the polymer-polypeptide in thecell seeding culture medium. That is, cell-cell interaction may occur inthe medium, and may be encouraged by the polymer-polypeptide in themedium, before the polymer-polypeptide attaches to the surface of thecell culture article.

Any type of cell may be used in accordance with the teachings presentedherein. For example, the cells may be connective tissue cells such asepithelial and endothelial cells, hepatocytes, skeletal or smooth musclecells, heart muscle cells, intestinal cells, kidney cells, or cells fromother organs, stem cells, islet cells, blood vessel cells, lymphocytes,cancer cells, or the like. The cells may be mammalian cells, preferablyhuman cells, but may also be non-mammalian cells such as bacterial,yeast, or plant cells.

In numerous embodiments, the cells are stem cells which, as generallyunderstood in the art, refer to cells that have the ability tocontinuously divide (self-renewal) and that are capable ofdifferentiating into a diverse range of specialized cells. In someembodiments, the stem cells are multipotent, totipotent, or pluripotentstem cells that are isolated from an organ or tissue of a subject. Suchcells are capable of giving rise to a fully differentiated or maturecell types. A stem cell may be a bone marrow-derived stem cell,autologous or otherwise, a neuronal stem cell, or an embryonic stemcell. A stem cell may be nestin positive. A stem cell may be ahematopoeietic stem cell. A stem cell may be a multi-lineage cellderived from epithelial and adipose tissues, umbilical cord blood,liver, brain or other organ. In various embodiments, the stem cells areundifferentiated stem cells, such as undifferentiated embryonic stemcells.

Prior to seeding cells, the cells may be harvested and suspended in asuitable medium, such as a growth medium in which the cells are to becultured once seeded onto the surface. As described above, the mediummay include the polymer-polypeptide that will form a coating whenincubated on a cell culture surface in the medium under cell cultureconditions. For example, the cells may be suspended in and cultured in aserum-containing medium, a conditioned medium, or a chemically-definedmedium. As used herein, “chemically-defined medium” means cell culturemedia that contains no components of unknown composition. Chemicallydefined media may, in various embodiments, contain no proteins,hydrosylates, or peptides of unknown composition. In some embodiments,conditioned media contains polypeptides or proteins of knowncomposition, such as recombinant growth hormones. Because all componentsof chemically-defined media have a known chemical structure, variabilityin culture conditions and thus cell response can be reduced, increasingreproducibility. In addition, the possibility of contamination isreduced.

One or more growth or other factors may be added to the medium in whichcells are incubated. The factors may facilitate cellular proliferation,adhesion, self-renewal, differentiation, or the like. Examples offactors that may be added to or included in the medium include musclemorphogenic factor (MMP), vascular endothelium growth factor (VEGF),interleukins, nerve growth factor (NGF), erythropoietin, plateletderived growth factor (PDGF), epidermal growth factor (EGF), activin A(ACT), hematopoietic growth factors, retinoic acid (RA), interferons,fibroblastic growth factors, such as basic fibroblast growth factor(bFGF), bone morphogenetic protein (BMP), peptide growth factors,heparin binding growth factor (HBGF), hepatocyte growth factor, tumornecrosis factors, insulin-like growth factors (IGF) I and II,transforming growth factors, such as transforming growth factor-β1(TGFβ1), and colony stimulating factors.

The cells may be seeded at any suitable concentration. Typically, thecells are seeded at about 10,000 cells/cm² of substrate to about 500,000cells/cm². For example, cells may be seeded at about 50,000 cells/cm² ofsubstrate to about 150,000 cells/cm². However, higher and lowerconcentrations may readily be used. The incubation time and conditions,such as temperature, CO₂ and O₂ levels, growth medium, and the like,will depend on the nature of the cells being cultured and can be readilymodified. The amount of time that the cells are incubated on the surfacemay vary depending on the cell response desired.

The cultured cells may be used for any suitable purpose, including (i)obtaining sufficient amounts of undifferentiated stem cells cultured ona synthetic surface in a chemically defined medium for use ininvestigational studies or for developing therapeutic uses, (ii) forinvestigational studies of the cells in culture, (iii) for developingtherapeutic uses, and (iv) for therapeutic purposes.

Aspects

A variety of aspects of compositions, methods, and articles have beendescribed herein. A summary of a few select examples of suchcompositions, methods, and articles are provided below.

In a 1^(st) aspect, an aqueous cell culture medium composition comprises(i) an aqueous cell culture solution configured to support the cultureof mammalian cells; and (ii) a synthetic polymer conjugated to apolypeptide dissolved in the aqueous cell culture solution, wherein thesynthetic polymer conjugated to a polypeptide is configured to attach tothe surface of a cell culture article under cell culture conditions, andwherein incubation of the aqueous cell culture medium composition on acell culture surface under cell culture conditions results is attachmentto the surface of the synthetic polymer conjugated to the polypeptide.

A 2^(nd) aspect is a composition of the 1^(st) aspect, wherein the cellculture medium composition is a chemically defined composition.

A 3^(rd) aspect is a composition of the 1^(st) or 2^(nd) aspect, whereinthe cell culture medium is free of animal derived components.

A 4^(th) aspect is an aqueous cell culture medium composition comprising(i) an aqueous cell culture solution configured to support the cultureof mammalian cells; and (ii) a synthetic polymer conjugated to apolypeptide dissolved in the aqueous cell culture solution, wherein thepolymer is selected from the group consisting of a polymer that has alinear backbone and is crosslink free, a polymer that has a branchedbackbone and is crosslink free, and a star polymer free of crosslinks,and wherein the synthetic polymer conjugated to the polypeptide issoluble in water at 20° C. or less, wherein the composition issubstantially free of organic solvents, and wherein incubation of theaqueous cell culture medium compositin on a cell culture surface undercell culture conditions results in attachment to the surface of thesynthetic polymer conjugated to the polypeptide.

A 5^(th) aspect is a composition of the 4^(th) aspect, wherein asubstantially similar polymer that is not conjugate to the polypeptideis insoluble in water at 37° C.

A 6^(th) aspect is a composition of the 4^(th) or 5^(th) aspects,wherein the polymer has a linear backbone and is crosslink free.

A 7^(th) aspect is a composition of any of aspects 4-6, wherein the cellculture medium is free of animal derived components.

An 8^(th) aspect is a composition of any of aspects 4-7, wherein thecell culture medium composition is a chemically defined composition.

A 9^(th) aspect is a composition of any of aspects 4-8, wherein thepolymer is formed from no monomers having di- or higher-functionality.

An 10^(th) aspect is a composition of any of aspects 4-9, wherein thepolymer is formed from at least one monomer comprising a conjugatedpolypeptide.

An 11^(th) aspect is a composition of the 10^(th) aspect, wherein the atleast one monomer comprising a conjugated polypeptide is methacrylicacid.

A 12^(th) aspect is a composition of any of aspects 4-11, wherein thepolymer is formed from polymerization of (i) methacrylic acid conjugatedto the polypeptide and (ii) hydroxyethylmethacrylate.

A 13^(th) aspect is a composition the 11^(th) aspect, wherein the molarratio of the methacrylic acid conjugated to the polypeptide and thehydroxyethylmethacrylate is between 1 to 15 and 1 to 5.

A 14^(th) aspect is a composition of the 11^(th) aspect, wherein themolar ratio of the methacrylic acid conjugated to the polypeptide andthe hydroxyethylmethacrylate is about 1 to 9.

A 15^(th) aspect is a composition of any of aspects 4-13, wherein thepolymer is formed from polymerization of hydroxyethylmethacrylate andMAA-PEO₄-polypeptide, wherein MAA is methacrylic acid, and PEO ispolyethylene oxide.

A 16^(th) aspect is a composition of any of aspects 4-15, wherein theweight percentage of the polypeptide relative to the polymer conjugatedto the polypeptide is greater than 10%.

A 17^(th) aspect is a composition of any of aspects 4-15, wherein theweight percentage of the polypeptide relative to the polymer conjugatedto the polypeptide is greater than 40%.

A 18^(th) aspect is a composition of any of aspects 4-17, wherein thepolypeptide is a cell adhesive polypeptide.

A 19^(th) aspect is a composition of any of aspects 4-18, wherein thepolypeptide comprises an RGD sequence.

An 20^(th) aspect is a composition of any of aspects 4-19, wherein thepolypeptide is a selected from the group of a vitronectin polypeptide, acollagen polypeptide, of a laminin polypeptide, a bone sialoproteinpolypeptide, and a fibronectin polypeptide.

A 21^(st) aspect is a composition of any of aspects 4-20, wherein thepolypeptide is a vitronectin polypeptide.

A 22^(nd) aspect is a composition of any of aspects 4-21, wherein thepolypeptide comprises an amino acid sequence of SEQ ID NO:27.

A 23^(rd) aspect is a composition of any of aspects 4-22, wherein thepolymer conjugated to the polypeptide has a molecular weight of between10 kilodaltons and 1000 kilodaltons.

A 24^(th) aspect is a composition of any of aspects 4-23, wherein thecomposition has a pH of between 7 and 8, and further comprises: glucoseand one or more amino acids.

A 25^(th) aspect is a composition of any of aspects 4-24, furthercomprising cells.

A 26^(th) aspect is a composition of the 25^(th) aspect, wherein thecells are stem cells.

A 27^(th) aspect is a composition of the 25^(th) aspect, wherein thecells are human embryonic stem cells or human mesenchymal stem cells.

A 28^(th) aspect is a composition of any of aspects 4-27, wherein thecomposition is free of microcarriers.

A 29^(th) aspect is a composition of any of aspects 4-27, wherein thecell culture surface is the surface of a microcarrier,

A 30^(th) aspect is a method for coating a surface of a cell culturearticle, comprising: (i) introducing a synthetic polymer having acovalently attached polypeptide to an aqueous cell culture medium toproduce a polymer containing cell culture medium, wherein the syntheticpolymer conjugated to a polypeptide is configured to attach to thesurface of a cell culture article under cell culture conditions; (ii)disposing the polymer containing cell culture medium on the surface ofthe cell culture article to produce a coated article; and (iii)incubating the coated article in the medium under cell cultureconditions to attach the synthetic polymer conjugated to the polypeptideto the surface of the cell culture article.

A 31^(st) aspect is a method of the 30^(th) aspect, wherein the cellculture medium composition is a chemically defined composition.

A 32^(nd) aspect is a method of the 30^(th) or 31^(st) aspect, whereinthe cell culture medium is free of animal derived components.

A 33^(rd) aspect is a method for coating a surface of a cell culturearticle, comprising: (i) introducing a polymer having a covalentlyattached polypeptide to an aqueous cell culture medium to produce apolymer containing cell culture medium, wherein the polymer is selectedfrom the group consisting of a polymer that has a linear backbone and iscrosslink free, a polymer that has a branched backbone and that iscrosslink free, and a star polymer that is crosslink free, wherein thepolymer having the covalently attached polypeptide is soluble at 20° C.or less, wherein the aqueous solution is substantially free of organicsolvents; (ii) disposing the polymer containing cell culture medium onthe surface of the cell culture article to produce a coated article; and(iii) incubating the coated article in the medium under cell cultureconditions to attach the polymer conjugated to the polypeptide to thesurface of the cell culture article.

A 34^(th) aspect is a method of the 33^(rd) aspect, wherein the polymerhas a linear backbone.

A 35^(th) aspect is a method of the 31^(st) or 32^(nd) aspect, whereinthe cell culture medium is free of animal derived components.

A 36^(th) aspect is a method of any of aspects 33-35, wherein the cellculture medium composition is a chemically defined composition. A37^(th) aspect is a method of any of aspects 33-36, wherein incubatingthe coated article in the medium under cell culture conditions includesincubating the coated article in the medium at about 37° C.

A 38^(th) aspect is a method of any of aspects 33-34, wherein asubstantially similar polymer that it not conjugated to the polypeptideis insoluble in water at 25° C.

A 39^(th) aspect is a method of any of aspects 33-38, wherein the weightpercentage of the polypeptide relative to the polymer conjugated to thepolypeptide is greater than 10%.

A 40^(th) aspect is a method of any of aspects 33-38, wherein the weightpercentage of the polypeptide relative to the polymer conjugated to thepolypeptide is greater than 40%.

A 41^(st) aspect is a method of any of aspects 33-40, wherein thepolypeptide is a cell adhesive polypeptide.

A 42^(nd) aspect is a method of any of aspects 33-41, wherein thepolypeptide comprises an RGD sequence.

A 43^(rd) aspect is a method of any of aspects 33-42, wherein thepolypeptide is a selected from the group of a vitronectin polypeptide, acollagen polypeptide, of a laminin polypeptide, a bone sialoproteinpolypeptide, and a fibronectin polypeptide.

A 44^(th) aspect is a method of any of aspects 33-43, wherein thepolypeptide is a vitronectin polypeptide.

A 45^(th) aspect is a method of any of aspects 33-44, wherein thepolypeptide comprises an amino acid sequence of SEQ ID NO:27.

A 46^(th) aspect is a method of any of aspects 33-45, wherein thepolymer is formed from at least one monomer comprising a conjugatedpolypeptide.

A 47^(th) aspect is a method of the 46^(th) aspect, wherein the at leastone monomer comprising a conjugated polypeptide is methacrylic acid.

A 48^(th) aspect is a method of the 46^(th) aspect, wherein the polymeris formed from polymerization of (i) methacrylic acid conjugated to thepolypeptide and (ii) hydroxyethylmethacrylate.

A 49^(th) aspect is a method of any of aspects 33-45, wherein thepolymer is formed from polymerization of a (i) monomer comprising amethacrylic acid functional group and (ii) hydroxyethmethacrylate.

A 50^(th) aspect is a method of any of aspects 33-49, wherein thepolymer conjugated to the polypeptide has a molecular weight of between10 kilodaltons and 1000 kilodaltons.

A 51^(st) aspect is a method of any of aspects 33-50, wherein thesurface of the substrate has a water contact angle between 0° and 50°.

A 52^(nd) aspect is a method of any of aspects 33-50, wherein thesurface of the substrate has a water contact angle between 0° and 30°.

A 53^(rd) aspect is a method of any of aspects 33-52, wherein thesurface of the substrate is a plasma treated polystyrene surface.

A 54^(th) aspect is a method for culturing cells, comprising: (i)introducing cells into a polymer-containing cell culture medium, whereinthe polymer containing cell culture medium comprises a synthetic polymerhaving a covalently attached polypeptide, wherein the synthetic polymerconjugated to a polypeptide is configured to attach to the surface of acell culture article under cell culture conditions; (ii) contacting thepolymer containing cell culture medium and cells to a surface of a cellculture article to produce a coated article; and (iii) incubating thecells on the coated article in the medium under cell culture conditions,wherein incubating the coated article in the medium under cell cultureconditions results in attachment of the synthetic polymer conjugated tothe polypeptide to the surface of the cell culture article.

A 55^(th) aspect is a method of the 54^(th) aspect, wherein the cellculture medium is free of animal derived components.

A 56^(th) aspect is a method of the 54^(th) or 55^(th) aspect, whereinthe cell culture medium composition is a chemically defined composition.

A 57^(th) aspect is a method for culturing cells, comprising: (i)introducing cells into a polymer-containing cell culture medium, whereinthe polymer containing cell culture medium comprises a polymer having acovalently attached polypeptide, wherein the polymer is selected fromthe group consisting of a polymer that has a linear backbone and iscrosslink free, a polymer that has a branched backbone and is crosslinkfree, and a star polymer that is crosslink free, wherein the polymerhaving the covalently attached polypeptide is soluble in water at 20° C.or less, wherein the aqueous solution is substantially free of organicsolvents; (ii) contacting the polymer containing cell culture medium andcells to a surface of a cell culture article to produce a coatedarticle; and (iii) incubating the cells on the coated article in themedium under cell culture conditions, wherein incubating the coatedarticle in the medium under cell culture conditions results inattachment of the polymer conjugated to the polypeptide to the surfaceof the cell culture article.

A 58^(th) aspect is a method of the 57th aspect, wherein the polymer hasa linear backbone.

A 59^(th) aspect is a method of the 57^(th) or 58^(th) aspect, whereinthe cell culture medium is free of animal derived components.

A 60^(th) aspect is a method of any of aspects 57-59, wherein the cellculture medium composition is a chemically defined composition.

A 61^(st) aspect is a method of any of aspects 57-60, wherein incubatingthe coated article in the medium under cell culture conditions includesincubating the coated article in the medium at about 37° C.

A 62^(nd) aspect is a method of any of aspects 57-61, wherein asubstantially similar polymer that it not conjugated to the polypeptideis insoluble in water at 25° C.

A 63^(rd) aspect is a method of any of aspects 57-62, wherein the weightpercentage of the polypeptide relative to the polymer conjugated to thepolypeptide is greater than 40%.

A 64^(th) aspect is a method of any of aspects 57-63, wherein the weightpercentage of the polypeptide relative to the polymer conjugated to thepolypeptide is greater than 60%.

A 65^(th) aspect is a method of any of aspects 57-64, wherein thepolypeptide is a cell adhesive polypeptide.

A 66^(th) aspect is a method of any of aspects 57-65, wherein thepolypeptide comprises an RGD sequence.

A 67^(th) aspect is a method of any of aspects 57-66, wherein thepolypeptide is a selected from the group of a vitronectin polypeptide, acollagen polypeptide, of a laminin polypeptide, a bone sialoproteinpolypeptide, and a fibronectin polypeptide.

A 68^(th) aspect is a method of any of aspects 57-67, wherein thepolypeptide is a vitronectin polypeptide.

A 69^(th) aspect is a method of any of aspects 57-69, wherein thepolypeptide comprises an amino acid sequence of SEQ ID NO:27.

A 70^(th) aspect is a method of any of aspects 57-69, wherein thepolymer is formed from at least one monomer comprising a conjugatedpolypeptide.

A 71^(st) aspect is a method of the 70^(th) aspect, wherein the at leastone monomer comprising a conjugated polypeptide is methacrylic acid.

A 72^(nd) aspect is a method of the 70^(th) aspect, wherein the polymeris formed from polymerization of (i) methacrylic acid conjugated to thepolypeptide and (ii) hydroxyethylmethacrylate.

A 73^(rd) aspect is a method of any of aspects 57-69, wherein thepolymer is formed from polymerization of a (i) monomer comprising amethacrylic acid functional group and (ii) hydroxyethmethacrylate.

A 74^(th) aspect is a method of any of aspects 59-73, wherein thepolymer conjugated to the polypeptide has a molecular weight of between10 kilodaltons and 1000 kilodaltons.

A 75^(th) aspect is a method of any of aspects 57-74, wherein thesurface of the substrate has a water contact angle between 0° and 50°.

A 76^(th) aspect is a method of any of aspects 57-75, wherein thesurface of the substrate has a water contact angle between 0° and 30°.

A 77^(th) aspect is a method of any of aspects 57-76, wherein thesurface of the substrate is a plasma treated polystyrene surface.

A 78^(th) aspect is a method of any of aspects 57-77, wherein the cellsare stem cells.

A 79^(th) aspect is a method of the 78^(th) aspect, wherein the cellsare human embryonic stem cells or human mesenchymal stem cells.

Non-limiting examples of compositions, methods, and articles describedherein are presented below for purposes of example.

EXAMPLES Example 1: Culture on Pre-Coated Substrate Vs. Polymer inMedium

Cells were cultured in 6-well plates that were either pre-coated withMesenCult-XF Attachment Substrate (“MC-ASB”) (StemCell Technologies,Cat. No. 05424), poly(HEMA-co-MAA-PEO4-VN) (“polyHEMA-co-VN”), oruncoated Corning CellBIND® plates (Corning Cat. No. 3335) or Costar®TC-treated plates (Corning Cat. No. 3516). PolyHEMA-co-VN was preparedas described as follows. Briefly, peptide monomer MAA-PEG4-VN(methacrylic acid-[polyethylene glycol]₄-vitronectin, where vitronectinhas an amino acid sequence of SEQ ID NO:27) was purchased from AmericanPeptide Company Inc. who synthesized the molecule using a solid peptidesynthesizer. This monomer was copolymerized using 1:9 molar ratio withhydroxyethyl methacrylate (HEMA) in ethanol using thermal free radicalpolymerization and obtained the final polyHEMA-co-VN peptide copolymer.

For uncoated plates, MC-ASB or polyHEMA-co-VN was added to the cellculture medium and plated along with cells. Cell culture medium wasMesenCult-XF complete medium (“MC-XF”) Basal Medium (StemCellTechnologies, Cat. No. 054020), which included MesenCult-XF Basal Medium(StemCell Technologies, Cat. No. 05421), MesenCult-XF Supplement (5×)(StemCell Technologies, Cat. No. 05422) and 2 mM L-Glutamine (Stem CellTechnologies, Cat. No. 07100).

A. Preparation of Pre-Coated Vessels

i. MesenCult Attachment Substrate

MC-ASB was pre-coated following the manufacturer's instructions.Briefly, MC-ASB was dissolved in water at a concentration of 1 mg/ml asa stock solution. For coating, the MC-ASB stock solution was furtherdiluted 1:28 in sterile PBS without Ca++ or Mg++ (Life Technologies catno. 14190) and 0.8 ml was added per well to a TCT plate. The plate wasstored in a covered Nalgene container overnight at 4° C. for proteinadsorption. Before cell culture, the plate was allowed to warm to roomtemperature for 20-30 minutes and washed with sterile cell culture waterdown the edge of well. The water was swirled around to rinse the entiresurface and then aspirated off.

ii. polyHEMA-co-VN

Gamma sterilized polyHEMA-co-VN powder was reconstituted aseptically toa concentration of 2 mg/ml in sterile tissue culture water to generate astock solution. The stock solution was gently rocked back and forth andallowed to dissolve for 5 minutes at room temperature. In a CELLBind®6-well plate, 25 μl of polymer stock solution was diluted into 1 ml ofsterile water in each well and incubated at 37° C. for 1 hour. The platewas washed with sterile cell culture water down the edge of each well ofthe plate. The water was swirled around to rinse the entire surface andthen aspirated off.

iii. Matrigel

Matrigel® was diluted 1:30 and coated on TCT 6-well plates as a controlsurface for hESC seeding and subsequent culture.

B. Cell Culture

i. hMSCs

Bone-marrow derived stem cells donor #2637, p4 cells were propagated onMC-ASB pre-coated surface in MC-XF. Cells were passaged when the cellsreached 80% confluency. Cells were briefly rinsed with dPBS (LifeTechnologies, cat no. 14190) and then incubated with MesenCult-ACFEnzymatic Dissociation solution (StemCell Tech cat, no. 05427) for about2 minutes. The cells were gently tapped from the surface, pipetted upand down a few times and then transferred to a 15 ml centrifuge tube.The flask was then rinsed with MesenCult-ACF Enzyme Inhibition solution(StemCell Tech, cat no. 05428) and then added to the tube containing thecells. The cells were spun down at 1200-1500 RPM for 6 minutes. Cellcounts and viability were obtained from a Vi-Cell, automated cellviability analyzer (Beckman-Coulter). The pre-coated MC-ASB plate,CellBIND and pre-coated polyHEMA-co-VN plate were seeded with hMSC cellsin MC-XF at a cell density of 3500 cells/cm². For uncoated plates, cellsuspension was further supplemented with 0.05 mg/ml, 0.025 mg/ml, 0.012mg/ml and 0.006 mg/ml of polyHEMA-co-VN or 0.037 mg/ml and 0.0074 mg/mlof MC-ASB using corresponding stock solution. 4 ml of cell mixturesuspension with or without attachment supplement was added to each well.The medium was changed every 2-3 days during the cultures.

a. Cell Count and Staining

Cells cultured under each condition were harvested from 4 to 5 wells ofthe 6-well plate and pooled together and transferred into a 15 mlcentrifuge tube containing 1 ml of Fetal Bovine Serum (LifeTechnologies, Cat no, 16000). All wells were then rinsed with dPBS andadded to the cell suspension in the 15 ml tube. Cells were spun down at1200-1500 RPM for 5-6 minutes and then resuspended in 3-5 mls of MC-XF.Cell count and viablity were obtained from Vi-Cell. To show theuniformity of the cell coverage, one well on each plate was crystalviolet stain solution.

ii. hESCs

Human ESC-BGO1v was purchased from Life Technology and was used fortesting in control or experimental conditions. Chemically defined mediummTeSR1 was purchased from Stem Cell Technology and used as standardmedium for all hESC culture experiments reported here. Matrigel® waspurchased from BD Sciences. CellBind and TCT 6-well plates werepurchased from Corning Life Sciences.

PolyHEMA-co-VN was added in mTeSR1 at concentration of 0.006 mg/ml to0.025 mg/ml and mixed with BGO1v cells for seeding in CellBind 6-wellplates.

Cells were seeded at 0.8×10⁶ per well and feed everyday after 2 days. Nopolymer was supplemented in medium during re-feeding. Cell morphologywas observed using optical microscopy every day. Cell count andviability were obtained from Vi-Cell after 4 days.

C. Results and Discussion

i. hMSCs

FIG. 5 presents images of cells cultured on wells of 6-well TCT plate,where the wells were (a) pre-coated with MC-ASB, (b) uncoated, but theseeding cell culture medium contained 0.037 mg/ml MC-ASB, and (c)uncoated, but the seeding cell culture medium contained 0.0074 mg/mlMC-ASB. As shown, pre-coated MC-ASB supported normal attachment andproliferation of hMSC (FIG. 5a ). In contrast, addition of MC-ASB tocell culture medium and plating onto uncoated surfaces did not providesimilar attachment support for hMSCs at the tested concentrations of0.037 mg/ml (FIG. 5b ) or 0.0074 mg/ml (FIG. 5c ).

We selected 0.037 mg/ml and 0.0074 mg/ml MC-ASB concentrations because,0.037 mg/ml was the concentration of MC-ASB solution used to pre-coatMC-ASB, which provided successful cell performance, and 0.0074 mg/mlprovided the same amount of material in each well in the pre-coatedwells. Due to 4 ml higher volume of medium used in cell culture vs. 0.8ml used in pre-coating process, 5× dilution was applied.

In contrast to MC-ASB, polyHEMA-co-VN supplemented in medium effectivelysupported growth of hMSC. This growth was comparable to the surfacepre-coated with polyHEMA-co-VN. Without polyHEMA-co-VN, the medium alonefailed to do so. With reference to FIG. 6 images of hMSCs cultured onCellBind® surfaces with and without polyHEMA-co-VN are shown. Cellscultured on pre-coated polyHEMA-co-VN (FIG. 6a ), uncoated CellBind®without polyHEMA-co-VN added to seeding cell culture medium (FIG. 6b ),uncoated CellBind® with 0.006 mg/ml polyHEMA-co-VN added to seeding cellculture medium (FIG. 6c ), uncoated CellBind® with 0.012 mg/mlpolyHEMA-co-VN added to seeding cell culture medium (FIG. XX (6 d),uncoated CellBind® with 0.025 mg/ml polyHEMA-co-VN added to seeding cellculture medium (FIG. 6e ), and uncoated CellBind® with 0.050 mg/mlpolyHEMA-co-VN added to seeding cell culture medium (FIG. 6f ) areshown.

Referring now to FIG. 7, images of crystal violet-stained hMSCs culturedin different surfaces are shown. The images are of hMSCs cultured on (a)TCT surface pre-coated with MC-ASB; (b) non-pre-coated TCT surface withseeding medium supplemented with 0.037 mg/ml of MC-ASB; (c)non-pre-coated TCT surface with seeding medium supplemented with 0.0074mg/ml of MC-ASB; (d) polyHEMA-co-VN pre-coated CellBind® surface; (e)non-pre-coated CellBind® surface; (f) non-pre-coated CellBind® surfacewith seeding medium supplemented with 0.006 mg/ml polyHEMA-co-VN; (g)non-pre-coated CellBind® surface with seeding medium supplemented with0.012 mg/ml polyHEMA-co-VN; (h) non-pre-coated CellBind® surface withseeding medium supplemented with 0.025 mg/ml polyHEMA-co-VN; (i)non-pre-coated CellBind® surface with seeding medium supplemented with0.050 mg/ml polyHEMA-co-VN.

As shown in FIG. 7, pre-coated MC-ASB plates (a) support hMSCattachment, but not non-precoated plates where the seeding culturemedium was supplemented with MC-ASB did not support attachment (b-c). Incontrast, both pre-coated polyHEMA-co-VN plates (d) and non-pre-coatedpolyHEMA-co-VN plates where the seeding cell culture medium wassupplemented with polyHEMA-co-VN (f-g) supported hMSC attachement.Uncoated CellBind® plates in which polyHEMA-co-VN was not added to theseeding medium did not perform well for hMSC attachment (e).

Referring now to FIG. 8, a graph showing the percentage of viable cellsobserved each of the polyHEMA-co-VN and MC-ASB surfaces is shown. Whilethe number of cells attached to the various surfaces varied, theviability of those that did attach was near 100% for all surfacestested.

Referring now to FIG. 9, a graph showing the number of cell thatattached to each of the polyHEMA-co-VN and MC-ASB surfaces is shown.These results confirm the results shown above and discussed with regardto FIG. 7. That is, pre-coated MC-ASB supported attachment and growth,while un-pre-coated wells where MC-ASB was added to the seeding culturemedium did not support attachment. In contrast, both un-pre-coated wellswhere polyHEMA-co-VN was added to the seeding medium and pre-coatedpolyHEMA-co-VN surfaces supported attachment of hMSCs.

These results suggest that polyHEMA-co-VN, but not MC-ASB, canefficiently be adsorbed to the substrate surface from medium and quicklyprovides for hMSCs attachment and growth. With increase of polymerconcentration of polyHEMA-co-VN, the cell numbers decreased withouteffecting cell morphology and surface coverage. Extra polymer left overin the solution after absorption may reduce the cell attachment but theimpact was minimal. This suggests that this polymer has littleside-effect to hMSC in medium and is safe for the cell culture.

In conclusion, polyHEMA-co-VN can be used as medium supplement to enablehMSC attachment and growth directly on traditional cell culturesubstrates. This polymer may provide a new way to make syntheticchemically defined media for cell therapeutic applications.

ii. hESCs

As with hMSCs, the addition of polyHEMA-co-VN to seeding cell culturemedium supported hESC attachment and growth on non-pre-coated surfaces.

Referring now to FIG. 10, images of hESCs at day 2 are shown onMatrigel® coated TCT plates (c) and on un-pre-coated CellBind® plates inwhich the cell seeding medium was supplemented with 0.006 mg/mlpolyHEMA-co-VN (b) or 0.25 mg/ml polyHEMA-co-VN (a) are shown. As shown,the hESC attached and spread very well in 0.006 mg/ml concentrationpolyHEMA-co-VN which was comparable to Matrigel surface as shown in FIG.10b and FIG. 10c . When the seeding medium was supplemented with 0.025mg/ml, more clusters of the cells was observed, which suggests moreinteraction between cells as shown in FIG. 10 a.

Referring now to FIG. 11, images of hESCs at day 4 are shown onMatrigel® coated TCT plates (c) and on un-pre-coated CellBind® plates inwhich the cell seeding medium was supplemented with 0.006 mg/mlpolyHEMA-co-VN (b) or 0.25 mg/ml polyHEMA-co-VN (a) are shown. When thelower concentration polyHEMA-co-VN was used to supplement the seedingmedium, the cells continued to maintain good morphology comparable tothe Matrigel® coated surface as shown in FIG. 11b and FIG. 11c .Continued attachment and growth was also observed with the higherconcentration polyHEMA-co-VN (FIG. 11a ).

Referring now to FIG. 12, a graph of cell number after four days ofculture on Matrigel®, un-pre-coated surfaces where the seeding mediumwas supplement with 0.025 mg/ml polyHEMA-co-VN, and un-pre-coatedsurfaces where the seeding medium was supplement with 0.0.006 mg/mlpolyHEMA-co-VN are shown. As shown in FIG. 12, the final cell number iscomparable between Matrigel control and supplemented polyHEMA-co-VN.

Overall, the higher concentration polyHEMA-co-VN resulted in more cellclustering and a more cystic morphology. However, the cell number wasnot affected. These results suggested that concentration of the polymerin medium may affect how an added peptide polymer will interact withcells and cells clusters.

Thus, embodiments of SYNTHETIC ATTACHMENT MEDIUM FOR CELL CULTURE aredisclosed. One skilled in the art will appreciate that the compositions,coatings, articles, methods, etc. described herein can be practiced withembodiments other than those disclosed. The disclosed embodiments arepresented for purposes of illustration and not limitation.

What is claimed is:
 1. A cell culture composition, comprising: anaqueous cell culture medium composition, said aqueous cell culturemedium composition comprising glucose and at least one amino acid, and asynthetic copolymer conjugated to a polypeptide dissolved in the aqueouscell culture medium composition, wherein the synthetic copolymer isformed from copolymerization of (i) methacrylic acid conjugated to thepolypeptide and (ii) hydroxyethylmethacrylate; and a cell culturearticle, said cell culture article comprising a surface; whereinincubation of the aqueous cell culture medium composition during cellculture results in attachment of the synthetic copolymer conjugated tothe polypeptide on the surface of the cell culture article.
 2. Thecomposition of claim 1, wherein the cell culture medium composition is achemically defined composition.
 3. The composition of claim 1, whereinthe copolymer has a linear backbone and is crosslink free, wherein thesynthetic copolymer conjugated to the polypeptide is soluble in water at20° C. or less, and wherein the composition is substantially free oforganic solvents.
 4. The composition of claim 2, wherein the molar ratioof the methacrylic acid conjugated to the polypeptide and thehydroxyethylmethacrylate is between 1 to 50 and 1 to
 1. 5. Thecomposition of claim 1, wherein the copolymer is formed fromcopolymerization of the hydroxyethylmethacrylate andMAA-PEO₄-polypeptide, wherein MAA is the methacrylic acid, and PEO ispolyethylene oxide.
 6. The composition of claim 1, wherein the weightpercentage of the polypeptide relative to the copolymer conjugated tothe polypeptide is greater than 10%.
 7. The composition of claim 1,wherein the polypeptide is a cell adhesive polypeptide.
 8. Thecomposition of claim 1, wherein the polypeptide comprises an RGDsequence.
 9. The composition of claim 1, wherein the polypeptide is avitronectin polypeptide.
 10. The composition of claim 1, wherein thepolypeptide comprises an amino acid sequence of SEQ ID NO:27.
 11. Thecomposition of claim 1, wherein the copolymer conjugated to thepolypeptide has a molecular weight of between 10 kilodaltons and 1000kilodaltons.
 12. The composition claim 1, wherein the composition has apH of between 7 and
 8. 13. The composition of claim 1, furthercomprising cells.
 14. The composition of claim 1, wherein the surface ofthe cell culture article is formed from a ceramic, glass, plastic,polymer, copolymer, or combination thereof.
 15. The composition of claim1, wherein the surface of the cell culture article is formed fromsoda-lime glass, pyrex glass, vycor glass, quartz glass, silicon,poly(vinyl chloride), poly(vinyl alcohol), poly(methyl methacrylate),poly(vinyl acetate-co-maleic anhydride), poly(dimethylsiloxane)monomethacrylate, cyclic olefin polymers, fluorocarbon polymers,polystyrenes, polypropylene, polyethyleneimine, poly(styrene-co-maleicanhydride), or poly(ethylene-co-acrylic acid).
 16. A cell culturecomposition, comprising: a media supplement comprising a syntheticcopolymer conjugated to a polypeptide dissolvable in aqueous cellculture medium, wherein the synthetic copolymer is formed fromcopolymerization of (i) methacrylic acid conjugated to the polypeptideand (ii) hydroxyethylmethacrylate; an aqueous cell culture medium, saidaqueous cell culture medium composition comprising glucose and at leastone amino acid; and a cell culture article, said cell culture articlecomprising a surface; wherein incubation of said aqueous cell culturemedium comprising the cell culture media supplement during cell cultureresults in attachment of the synthetic copolymer conjugated to thepolypeptide on the surface of the cell culture article.
 17. Thecomposition of claim 16, wherein the copolymer has a linear backbone andis crosslink free, wherein the synthetic copolymer conjugated to thepolypeptide is soluble in water at 20° C. or less, and wherein thecomposition is substantially free of organic solvents.
 18. Thecomposition of claim 16 wherein cell culture media supplement is addedto cell culture media in a dry state.
 19. The composition of claim 17wherein cell culture media supplement is added to cell culture mediadissolved in water.
 20. The composition of claim 16, wherein the molarratio of the methacrylic acid conjugated to the polypeptide and thehydroxyethylmethacrylate is between 1 to 50 and 1 to
 1. 21. Thecomposition of claim 16, wherein the copolymer is formed fromcopolymerization of the hydroxyethylmethacrylate andMAA-PEO₄-polypeptide, wherein MAA is the methacrylic acid, and PEO ispolyethylene oxide.
 22. The composition of claim 16, wherein the weightpercentage of the polypeptide relative to the copolymer conjugated tothe polypeptide is greater than 10%.
 23. The composition of claim 16,wherein the polypeptide is a cell adhesive polypeptide.
 24. Thecomposition of claim 16, wherein the polypeptide comprises an RGDsequence.
 25. The composition of claim 24, wherein the polypeptide is avitronectin polypeptide.
 26. The composition of claim 16, wherein thepolypeptide comprises an amino acid sequence of SEQ ID NO:27.
 27. Thecomposition of claim 16, wherein the copolymer conjugated to thepolypeptide has a molecular weight of between 10 kilodaltons and 1000kilodaltons.
 28. The composition of claim 16, wherein the surface of thecell culture article is formed from soda-lime glass, pyrex glass, vycorglass, quartz glass, silicon, poly(vinyl chloride), poly(vinyl alcohol),poly(methyl methacrylate), poly(vinyl acetate-co-maleic anhydride),poly(dimethylsiloxane) monomethacrylate, cyclic olefin polymers,fluorocarbon polymers, polystyrenes, polypropylene, polyethyleneimine,poly(styrene-co-maleic anhydride), or poly(ethylene-co-acrylic acid).29. The composition of claim 16, wherein the cell culture article ischosen from multi-well plates, jars, petri dishes, flasks, beakers,glass bead microcarriers, polymer bead microcarriers, roller bottles,slides, tubes, cover slips, membranes, hollow fibers, cups, spinnerbottles, perfusion chambers, bioreactors, and fermenters.
 30. Thecomposition of claim 16, wherein the cell culture article is chosen frommulti-well plates, petri dishes, flasks, and beakers.
 31. A method,comprising: introducing a synthetic copolymer having a covalentlyattached polypeptide to an aqueous cell culture medium to produce acopolymer containing cell culture medium, wherein the aqueous cellculture medium comprises glucose and at least one amino acid, whereinthe synthetic copolymer is formed from copolymerization of (i)methacrylic acid conjugated to the polypeptide and (ii)hydroxyethylmethacrylate; wherein the synthetic copolymer conjugated toa polypeptide is configured to attach to the surface of a cell culturearticle under cell culture conditions; disposing the copolymercontaining cell culture medium on the surface of the cell culturearticle to produce a coated article; and incubating the coated articlein the medium under cell culture conditions to attach the syntheticcopolymer conjugated to the polypeptide to the surface of the cellculture article.
 32. The method of claim 31, wherein the cell culturemedium composition is a chemically defined composition.
 33. The methodof claim 32, wherein the copolymer has a linear backbone and iscrosslink free, wherein the copolymer having the covalently attachedpolypeptide is soluble in water at 20° C. or less, and wherein theaqueous solution is substantially free of organic solvents.